The importance of short range interactions in the development of acidic and catalytic properties of H, Na - MoR

✍ Scribed by I. Bankos; J. Valyon; D. Kallo

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 465 KB
• Volume: 5
• Category: Article
• ISSN: 0920-5861
• DOI: 10.1016/0920-5861(89)80027-6

✦ Synopsis

Adsorption microcalorimetry and lR spectroscopy are used to study the nature, number, strength and accessibility of acid sites in H, Na-MoR samples, ion exchanged to different degrees. The differential molar adsorption heat and the number of ammonia molecules adsorbed are considered as a measure of the acid strength and of the number of acid sites, respectively. Sanderson electronegativity model allows to predict the trends of the variation of the average acid strength with the chemical composition. The average differential heat of NH3 adsorption (q) and the stretching frequency of OH groups (v) are in linear correlation with the intermediate electronegativity (Sint.). Catalytic activities for the isomerization and disproportionation of m-xylene are in better and closer correlation with the number of acid sites of different strength and type than with the intermediate electronegativity (Sint.).